text: /*
   *  jsaes version 0.1  -  Copyright 2006 B. Poettering
   *
   *  This program is free software; you can redistribute it and/or
   *  modify it under the terms of the GNU General Public License as
   *  published by the Free Software Foundation; either version 2 of the
   *  License, or (at your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to the Free Software
   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   *  02111-1307 USA
   */
  
  /*
   * http://point-at-infinity.org/jsaes/
   *
   * This is a javascript implementation of the AES block cipher. Key lengths 
   * of 128, 192 and 256 bits are supported.
   *
   * The well-functioning of the encryption/decryption routines has been 
   * verified for different key lengths with the test vectors given in 
   * FIPS-197, Appendix C.
   *
   * The following code example enciphers the plaintext block '00 11 22 .. EE FF'
   * with the 256 bit key '00 01 02 .. 1E 1F'.
   *
   *    AES_Init();
   *
   *    var block = new Array(16);
   *    for(var i = 0; i < 16; i++)
   *        block[i] = 0x11 * i;
   *
   *    var key = new Array(32);
   *    for(var i = 0; i < 32; i++)
   *        key[i] = i;
   *
   *    AES_ExpandKey(key);
   *    AES_Encrypt(block, key);
   *
   *    AES_Done();
   *
   * Report bugs to: jsaes AT point-at-infinity.org
   *
   */
  
  /******************************************************************************/
  
  /* 
     AES_Init: initialize the tables needed at runtime. Call this function
     before the (first) key expansion.
  */
  
  function AES_Init() {
    AES_Sbox_Inv = new Array(256);
    for(var i = 0; i < 256; i++)
      AES_Sbox_Inv[AES_Sbox[i]] = i;
    
    AES_ShiftRowTab_Inv = new Array(16);
    for(var i = 0; i < 16; i++)
      AES_ShiftRowTab_Inv[AES_ShiftRowTab[i]] = i;
  
    AES_xtime = new Array(256);
    for(var i = 0; i < 128; i++) {
      AES_xtime[i] = i << 1;
      AES_xtime[128 + i] = (i << 1) ^ 0x1b;
    }
  }
  
  /* 
     AES_Done: release memory reserved by AES_Init. Call this function after
     the last encryption/decryption operation.
  */
  
  function AES_Done() {
    delete AES_Sbox_Inv;
    delete AES_ShiftRowTab_Inv;
    delete AES_xtime;
  }
  
  /*
     AES_ExpandKey: expand a cipher key. Depending on the desired encryption 
     strength of 128, 192 or 256 bits 'key' has to be a byte array of length 
     16, 24 or 32, respectively. The key expansion is done "in place", meaning 
     that the array 'key' is modified.
  */
  
  function AES_ExpandKey(key) {
    var kl = key.length, ks, Rcon = 1;
    switch (kl) {
      case 16: ks = 16 * (10 + 1); break;
      case 24: ks = 16 * (12 + 1); break;
      case 32: ks = 16 * (14 + 1); break;
      default: 
        alert("AES_ExpandKey: Only key lengths of 16, 24 or 32 bytes allowed!");
    }
    for(var i = kl; i < ks; i += 4) {
      var temp = key.slice(i - 4, i);
      if (i % kl == 0) {
        temp = new Array(AES_Sbox[temp[1]] ^ Rcon, AES_Sbox[temp[2]], 
  	AES_Sbox[temp[3]], AES_Sbox[temp[0]]); 
        if ((Rcon <<= 1) >= 256)
  	Rcon ^= 0x11b;
      }
      else if ((kl > 24) && (i % kl == 16))
        temp = new Array(AES_Sbox[temp[0]], AES_Sbox[temp[1]], 
  	AES_Sbox[temp[2]], AES_Sbox[temp[3]]);       
      for(var j = 0; j < 4; j++)
        key[i + j] = key[i + j - kl] ^ temp[j];
    }
  }
  
  /* 
     AES_Encrypt: encrypt the 16 byte array 'block' with the previously 
     expanded key 'key'.
  */
  
  function AES_Encrypt(block, key) {
    var l = key.length;
    AES_AddRoundKey(block, key.slice(0, 16));
    for(var i = 16; i < l - 16; i += 16) {
      AES_SubBytes(block, AES_Sbox);
      AES_ShiftRows(block, AES_ShiftRowTab);
      AES_MixColumns(block);
      AES_AddRoundKey(block, key.slice(i, i + 16));
    }
    AES_SubBytes(block, AES_Sbox);
    AES_ShiftRows(block, AES_ShiftRowTab);
    AES_AddRoundKey(block, key.slice(i, l));
  }
  
  /* 
     AES_Decrypt: decrypt the 16 byte array 'block' with the previously 
     expanded key 'key'.
  */
  
  function AES_Decrypt(block, key) {
    var l = key.length;
    AES_AddRoundKey(block, key.slice(l - 16, l));
    AES_ShiftRows(block, AES_ShiftRowTab_Inv);
    AES_SubBytes(block, AES_Sbox_Inv);
    for(var i = l - 32; i >= 16; i -= 16) {
      AES_AddRoundKey(block, key.slice(i, i + 16));
      AES_MixColumns_Inv(block);
      AES_ShiftRows(block, AES_ShiftRowTab_Inv);
      AES_SubBytes(block, AES_Sbox_Inv);
    }
    AES_AddRoundKey(block, key.slice(0, 16));
  }
  
  /******************************************************************************/
  
  /* The following lookup tables and functions are for internal use only! */
  
  AES_Sbox = new Array(99,124,119,123,242,107,111,197,48,1,103,43,254,215,171,
    118,202,130,201,125,250,89,71,240,173,212,162,175,156,164,114,192,183,253,
    147,38,54,63,247,204,52,165,229,241,113,216,49,21,4,199,35,195,24,150,5,154,
    7,18,128,226,235,39,178,117,9,131,44,26,27,110,90,160,82,59,214,179,41,227,
    47,132,83,209,0,237,32,252,177,91,106,203,190,57,74,76,88,207,208,239,170,
    251,67,77,51,133,69,249,2,127,80,60,159,168,81,163,64,143,146,157,56,245,
    188,182,218,33,16,255,243,210,205,12,19,236,95,151,68,23,196,167,126,61,
    100,93,25,115,96,129,79,220,34,42,144,136,70,238,184,20,222,94,11,219,224,
    50,58,10,73,6,36,92,194,211,172,98,145,149,228,121,231,200,55,109,141,213,
    78,169,108,86,244,234,101,122,174,8,186,120,37,46,28,166,180,198,232,221,
    116,31,75,189,139,138,112,62,181,102,72,3,246,14,97,53,87,185,134,193,29,
    158,225,248,152,17,105,217,142,148,155,30,135,233,206,85,40,223,140,161,
    137,13,191,230,66,104,65,153,45,15,176,84,187,22);
  
  AES_ShiftRowTab = new Array(0,5,10,15,4,9,14,3,8,13,2,7,12,1,6,11);
  
  function AES_SubBytes(state, sbox) {
    for(var i = 0; i < 16; i++)
      state[i] = sbox[state[i]];  
  }
  
  function AES_AddRoundKey(state, rkey) {
    for(var i = 0; i < 16; i++)
      state[i] ^= rkey[i];
  }
  
  function AES_ShiftRows(state, shifttab) {
    var h = new Array().concat(state);
    for(var i = 0; i < 16; i++)
      state[i] = h[shifttab[i]];
  }
  
  function AES_MixColumns(state) {
    for(var i = 0; i < 16; i += 4) {
      var s0 = state[i + 0], s1 = state[i + 1];
      var s2 = state[i + 2], s3 = state[i + 3];
      var h = s0 ^ s1 ^ s2 ^ s3;
      state[i + 0] ^= h ^ AES_xtime[s0 ^ s1];
      state[i + 1] ^= h ^ AES_xtime[s1 ^ s2];
      state[i + 2] ^= h ^ AES_xtime[s2 ^ s3];
      state[i + 3] ^= h ^ AES_xtime[s3 ^ s0];
    }
  }
  
  function AES_MixColumns_Inv(state) {
    for(var i = 0; i < 16; i += 4) {
      var s0 = state[i + 0], s1 = state[i + 1];
      var s2 = state[i + 2], s3 = state[i + 3];
      var h = s0 ^ s1 ^ s2 ^ s3;
      var xh = AES_xtime[h];
      var h1 = AES_xtime[AES_xtime[xh ^ s0 ^ s2]] ^ h;
      var h2 = AES_xtime[AES_xtime[xh ^ s1 ^ s3]] ^ h;
      state[i + 0] ^= h1 ^ AES_xtime[s0 ^ s1];
      state[i + 1] ^= h2 ^ AES_xtime[s1 ^ s2];
      state[i + 2] ^= h1 ^ AES_xtime[s2 ^ s3];
      state[i + 3] ^= h2 ^ AES_xtime[s3 ^ s0];
    }
  }
  